The invention relates to a centrifuge, particularly a separator. The centrifuge includes a centrifugal drum that includes a centrifugal chamber and a centrifugal chamber bottom part non-displaceable relative to the centrifugal drum. Also included is a piston slide axially displaceably arranged to be in and/or on the centrifugal drum. At least one seal is arranged in a surrounding groove on an outer circumference of the centrifugal drum bottom part and further arranged between the piston slide and the outer circumference of the centrifugal chamber bottom part to seal off a gap between the piston slide and the centrifugal chamber bottom part.
A separator of this type is known from German Patent Document DE 199 22 237 A1. The construction shown in this document can be operated, among other ways, with cooled sterile air as the control and cleaning fluid, and has been used particularly in areas with high hygienic requirements. However, a demand for improvement still exists with respect to hygiene in the area of the seal(s) in the gap between the axially displaceable piston slide and the centrifugal chamber bottom part and/or the centrifugal drum, in whose area deposits may occur. From German Patent Document DE 199 52 785 A1, a similar state of the art is known which results in similar problems although the seal is situated partially open in a gap.
Another state of the art device is known from U.S. Patent Document U.S. Pat. No. 4,322,362. Here, a seal is arranged on the upper edge of a drum bottom part on a step of the lower drum part constructed on the inner circumference, outside the lower drum part, a piston slide being axially movable. The seal has an upper, relatively long, free section which rests on the inner circumference of the piston slide. From a sanitary point of view, this arrangement has little advantage because a gap exists below the seal in which deposits may form. The relatively expensive seal is, among other things, not suitable for high centrifugal forces, as can be reached by modern separators (up to 3,500 g or more), since there is the risk that such high compressions of the seal on the wall to the piston slide occur which impair its function.
It is known from German Patent Document DE 653 294 to arrange a membrane between a drum bottom part and an exterior pressure ring. German Patent Document DE 1908949 A teaches the arrangement of a seal in a groove of the drum top part outside the drum, where sanitary problems inside the drum play no role.
From German Patent Document DE 33 05 216, a separator is known in which ducts, which lead to solids discharge nozzles, can be closed by a ring-shaped valve body which, on its top side, pointing to the ducts, has a groove which has an open construction axially upward and into which a seal is inserted which seals off the ducts between the drum top part and drum bottom part during the opening and closing.